From: William Tseng Date: Tue, 11 Mar 2025 10:06:26 +0000 (+0800) Subject: drm/i915/dsi: let HW maintain the HS-TRAIL timing X-Git-Tag: v6.16-rc1~144^2~20^2~63 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1ca3991f6400769427bf1a5ff55def328612a947;p=thirdparty%2Flinux.git drm/i915/dsi: let HW maintain the HS-TRAIL timing This change is to avoid over-specification of the TEOT timing parameter, which is derived from software in current design. Supposed that THS-TRAIL and THS-EXIT have the minimum values, i.e., 60 and 100 in ns. If SW is overriding the HW default, the TEOT value becomes 150 ns, approximately calculated by the following formula. DIV_ROUND_UP(60/50)*50 + DIV_ROUND_UP(100/50))*50/2, where 50 is LP Escape Clock time in ns. The TEOT value 150 ns is larger than the maximum value, around 136 ns if UI is 1.8ns, (105 ns + 12*UI, defined by MIPI DPHY specification). However, the TEOT value will meet the specification if THS-TRAIL is set to the HW default, instead of software overriding. The timing change is made for both data lane and clock lane. v1: initial version. v2: change clock lane dphy timings. v3: remove calculation of trail cnt. v4: rebase. Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13891 Cc: Ville Syrjala Cc: Jani Nikula Cc: Vandita Kulkarni Cc: Lee Shawn C Cc: Cooper Chiou Signed-off-by: William Tseng Acked-by: Vandita Kulkarni Link: https://lore.kernel.org/r/20250311100626.533888-1-william.tseng@intel.com Signed-off-by: Jani Nikula --- diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c index 402b7b2e18296..ef9a9d780bfc2 100644 --- a/drivers/gpu/drm/i915/display/icl_dsi.c +++ b/drivers/gpu/drm/i915/display/icl_dsi.c @@ -1840,14 +1840,13 @@ static void icl_dphy_param_init(struct intel_dsi *intel_dsi) struct intel_connector *connector = intel_dsi->attached_connector; struct mipi_config *mipi_config = connector->panel.vbt.dsi.config; u32 tlpx_ns; - u32 prepare_cnt, exit_zero_cnt, clk_zero_cnt, trail_cnt; - u32 ths_prepare_ns, tclk_trail_ns; + u32 prepare_cnt, exit_zero_cnt, clk_zero_cnt; + u32 ths_prepare_ns; u32 hs_zero_cnt; u32 tclk_pre_cnt; tlpx_ns = intel_dsi_tlpx_ns(intel_dsi); - tclk_trail_ns = max(mipi_config->tclk_trail, mipi_config->ths_trail); ths_prepare_ns = max(mipi_config->ths_prepare, mipi_config->tclk_prepare); @@ -1874,14 +1873,6 @@ static void icl_dphy_param_init(struct intel_dsi *intel_dsi) clk_zero_cnt = ICL_CLK_ZERO_CNT_MAX; } - /* trail cnt in escape clocks*/ - trail_cnt = DIV_ROUND_UP(tclk_trail_ns, tlpx_ns); - if (trail_cnt > ICL_TRAIL_CNT_MAX) { - drm_dbg_kms(display->drm, "trail_cnt out of range (%d)\n", - trail_cnt); - trail_cnt = ICL_TRAIL_CNT_MAX; - } - /* tclk pre count in escape clocks */ tclk_pre_cnt = DIV_ROUND_UP(mipi_config->tclk_pre, tlpx_ns); if (tclk_pre_cnt > ICL_TCLK_PRE_CNT_MAX) { @@ -1914,17 +1905,13 @@ static void icl_dphy_param_init(struct intel_dsi *intel_dsi) CLK_ZERO_OVERRIDE | CLK_ZERO(clk_zero_cnt) | CLK_PRE_OVERRIDE | - CLK_PRE(tclk_pre_cnt) | - CLK_TRAIL_OVERRIDE | - CLK_TRAIL(trail_cnt)); + CLK_PRE(tclk_pre_cnt)); /* data lanes dphy timings */ intel_dsi->dphy_data_lane_reg = (HS_PREPARE_OVERRIDE | HS_PREPARE(prepare_cnt) | HS_ZERO_OVERRIDE | HS_ZERO(hs_zero_cnt) | - HS_TRAIL_OVERRIDE | - HS_TRAIL(trail_cnt) | HS_EXIT_OVERRIDE | HS_EXIT(exit_zero_cnt));